Adhesive tapes and a process for the preparation thereof

ABSTRACT

The adhesive tape of the invention has an adhesive layer of excellent anchoring strength to its backing and high adhesive strength. It is obtained by providing an under coat layer of organopolysiloxane composed of SiO2, R3SiO0.5 and R2SiO units (wherein R represents a substituted or unsubstituted monovalent hydrocarbon radical) in which the whole organic groups comprise 0.2-10 molar percent of phenyl groups, 0.005-5 molar percent of vinyl groups and the remainder of substantially methyl group on the backing comprising a polyimide, polyamideimide or organic fluorine-containing polymer or metal foil and then placing thereon an adhesive layer comprising an organopolysiloxane.

I United States Patent 1 1 1111 3,839,075

Moriyama et al. Oct. 1, 1974 [54] ADHESIVE TAPES AND A PROCESS FOR2,857,356 10/1958 Goodwin 117 122 x THE pREPARATlON THEREOF 2,882,1834/1959 Bond et al. 117/122 2,979,420 4/1961 Harper l17/122 X 1Inventors: Yasuhiro Moriyama; Yasuo Mito, 2,989,419 6/1961 Lamason117/122 x both of Fukaya; Minoru 3,032,438 5/1962 Gaynes et al. 117/122X Takamimwa; Shiro Gomyo, both of 3,202,535 8/1965 Gaynes 117/122 XAnnaka all of Japan 3,406,820 10/1968 Bond .4 117/122 X 3,560,249 2/1971Chereshkevich et al. 117/126 X [73] Ass1gnees: Nitto Electric IndustrialCo. Ltd.,

gsaka-fu i fi sjhmetsu Chemical Primary ExaminerWil1iam D. Martin ompany0 apan Assistant Examiner-Bernard D. Pianalto [22] Filed: Feb. 28, 1972Attorney, Agent, or FirmMcGlew and Tuttle [21] Appl. No.: 229,748

[57] ABSTRACT [30] For ign A li ti P i it D t The adhesive tape of theinvention has an adhesive Mar. 4, 1971 Japan 46-11658 layer of excellentanchoring Strength to its backing Oct. 25, 1971 Japan 46-84492 and highadhesive Strength It is obtained by Providing an under coat layer oforganopolysiloxane composed 52 us. (31.... 117/76 A, 117/122 PF, 117/126GB, of S102 1 and Rzsiqmits (wherein R 1 17/1351, 17/1388 N, [17/1388Up, sents a substituted or unsubstltuted monovalent hydrol17/161 ZAcarbon rad1cal) 1n wh1ch the whole orgamc groups [51 Int. Cl. C09j 7/02c01111risfi Percent of Phenyl groups [58] Field of Search 117/76 A 122 P122 PF, 0.005-5 molar percent of vinyl groups and the remain- 1 17/122PA 122 PS 126 GB 161 ZA der of substantially methyl group on the backingcomprising a polyimide, polyamideimide or organic fluo- 56] ReferencesCited rine-containing polymer or metal foil and then placing UNITEDSTATES PATENTS thereon an adhesive layer comprising an organopolysi-2,732,318 l/1956 Keil 117/122 oxane' 2,751,314 6/1956 Keil 117/ 122 X 6Claims, 2 Drawing Figures PAIENTEDHBT H 1 3.839.075

F ig.2

ADHESIVE TAPES AND A PROCESS FOR THE PREPARATION THEREOF SUMMARY OF THEINVENTION The present invention relates to an adhesive tape havingdistinguished adhesive characteristics and comprising an adhesive layerhaving an excellent property of anchoring to a backing to which ithasbeen applied. The invention is also directed to a process for thepreparation of the tape.

BACKGROUND OF THE INVENTION AND PRIOR ART It is publicly known art thata pressuresensitive tape may be prepared by providing a siliconeadhesive layer obtained by condensation of a copolymer composed of SiOunits and (CH SiO units with organopolysiloxane gum on a backingcomprising polyimide, polyamideimide, an organic fluorine-containingpolymer or metal foil. However, the tape thus prepared has such demeritthat when it is used, for instance, for covering part of a rubber roll,its adhesive layer would be transferred to the surface to which it isapplied and cause various troubles in its utility, since the adhesivelayer itself has poor anchoring strength to the backing.

In order to increase the anchoring strength of such an adhesive tape,there have been proposed some known methods, for example, a method inwhich the surface of the backing is previously treated chemically withammonium complex of sodium or naphthalene solution of sodium in case thebacking comprises an organic fluorinecontaining polymer, and a method inwhich the surface of the backing is generally subjected to physicalabrasion treatment before it is applied with a silicone adhesive.However, the transference of the adhesive layer to the surface to whichthe tape is applied canriot be eliminated sufficiently even by any ofthose methods. The demerit of the transference is particularlyremarkable in case the tape is applied to a silicone rubber roll or thelike.

OBJECTS OF THE INVENTION An object of the present invention is toprovide an adhesive tape of high adhesive strength to various surfaces,in which the adhesive layer has an excellent property of anchoring toits backing. Another object of the present invention is to provide anadhesive tape which adheres by pressure firmly to the surfaces ofvarious materials such as silicone rubber, neoprene rubber, acrylicresin, glass and metal, and when peeled, does not leave its adhesivelayer on said surfaces but separates them entirely therefom. Stillanother object of the invention is to provide a process suitable for preparing an adhesive tape having the above-described characteristics.

DESCRIPTION OF THE INVENTION The adhesive tape according to the presentinvention is prepared by providing an under-coat layer oforganopolysiloxane (A) containing 0.2- molar percent,

based on the whole organic groups, of phenyl group, 0.0055 molar percentof vinyl group and the remainder of substantially methyl group on abacking which comprises polyimide, polyamideimide or an organicfluorine-containing polymer or metal foil at least at its surface andthen forming thereon an adhesive layer comprising a conventionalorganopolysiloxane (B), the organopolysiloxane (A) being obtained bypartial condensation reactions of 30-70 parts by weight of a copolymer(a) composed of SiO units and R SiO units (wherein R represents asubstituted or unsubstituted monovalent hydrocarbon group such asmethyl, ethyl, trifiuoropropyl, phenyl or vinyl group) in a molar ratioof from 1:04 to 1:1 with -30 parts by weight of a diorganopolysiloxane(b) composed of R SiO units (wherein R represents a substituted orunsubstituted monovalent hydrocarbon group), containing hydroxyl orvinyl groups at the end of its molecular chain, and having a viscosityof more than 100,000 centistokes at 25C. The adhesive tape of theinvention has the advantage that it has high adhesive strength tovarious surfaces and quite excellent anchoring strength to its backing.

The organopolysiloxane (A) containing the specified amounts of phenyland vinyl groups may be obtained by mixing under heating 30-70 parts byweight, preferably 40-60 parts by weight, of a copolymer (a) composed ofSiO units (Q units) and R SiO units (M units) in which the whole organicgroup R is a methyl group or a part thereof is replaced with a vinyl ora phenyl group, the two units being in a molar ratio of from 110.4 to1:1, preferably from 120.5 to 1:0.8, with 70-30 parts by weight,preferably 60-40 parts by weight, of a diorganopolysiloxane (b) of aviscosity of l00,000 centistokes (at 25C) or more, containing hydroxylor vinyl groups at the end of the molecular chain and a vinyl or aphenyl group in its main chain if necessary, to effect partialcondensation reactions. The organopolysiloxane thus obtained hasremarkable adhesive strength.

The reason for the limiting molar ratio of the Q units to the M units inthe range of from 1:04 to 1:1 is that, if the ratio is below 1:04, theresulting copolymer (a) would become hard and, on the other hand, if theratio is above 121, it would become oily. Thus, in both cases, adhesiveorganopolysiloxane (A) cannot be obtained. In the condensation of thecopolymer (a) with the diorganopolysiloxane (b), their amounts should be30-70 parts and 70-30 parts by weight, respectively, in order to obtainthe organopolysiloxane (A) of high adhesive strength.

In the organopolysiloxane (A), if the proportion of phenyl and vinylgroups to the whole of the organic groups is too small, the aimedimprovement in anchoring strength cannot be attained and, on the otherhand, if it is too large, firm adhesion (solidification) between theunder coat layer of the organopolysiloxane (A) and the adhesive layer ofthe organopolysiloxane (B) applied thereon cannot be attained. In thelatter case, the two layers sometimes separate from each other, or theadhesive layer in its entirety becomes turbid to reduce its commercialvalue. Accordingly, the proportions of phenyl and vinyl groups in thewhole organic groups should be 0.2-10 molar percent, preferably l-7molar percent and 0.0055 molar percent, preferably 0.1-2 molar percent,respectively. The remainder of the organic groups should be the methylgroup, but may contain a small amount of a substituted or unsubstitutedmonovalent hydrocarbon group such as the trifluoropropyl or the ethylgroup.

The adhesives of organopolysiloxane (B) used in the invention are knownones, such as an adhesive comprising an organopolysiloxane obtained bycondensation reaction of 30-70 parts by weight of a copolymer of SiOunits and (CI-I SiO units in molar ratio of from 1:04 to 1:1 and 70-30parts by weight of dimethylpolysiloxane gum (d) or an organopolysiloxanein which part of the dimethylpolysiloxane gum (d) contains phenylgroups. They are disclosed in the specifications of Japanese PatentPublication No. 5186/1955 and US. Pat. No. 2,857,356. As commercialproduct, for example, KR-l01 of Shinetsu Chemical Company and DC-280 ofDow Corning Corporation are available.

Backingto which the adhesive layer is applied, may be made frompolymides; polyamideimides; organic fluorine-containing polymers such aspolytetrafluoroethylene, polytrifluoromonochloroethylene and copolymerof tetrafluoroethylene-hexafluoropropylene; polyvinylfluoride;polyfluorovinyliden; copolymer of tetrafluoroethyleneethylene; glassfiber tapes and sheets coated with said polyimide, polyamideimides,organic fluorine-containing polymers; and foils of inorganic materialssuch as metals, for example, aluminum,

lead, platinum, gold and tin. As the polyimides, there may be usedpublicly known polyimides shown in the specifications of, for example,US Pat. No. 3,176,630 and British Pat. No. 903,271. As thepolyamideimides, there may be used publicly known ones shown in thespecifications of, for example, US. Pat. Nos. 3,260,691 and 3,347,828and British Pat. No. 1,056,564.

In the preparation of an adhesive tape according to the presentinvention, an under coat layer of an organopolysiloxane containing theabove suggested amounts of phenyl and vinyl groups is formed first onthe surface of the backing. Before this, the surface of the backing ispreferably subjected to the chemical or physical treatment as previouslydescribed. The application of the organopolysiloxane to the backing canbe facilitated by diluting it previously with an organic solvent sbch asbenzene, toluene, xylene, trichloroethylene or perchloroethylene. It ispreferred to blend previously about 0-10 percent by weight of a curingcatalyst such as benzoyl peroxide, dicumyl peroxide or ditert.-butylperoxide with the organopolysiloxane in order to harden it completelyafter the application. Drying after the application may be effected bymerely air-drying but drying under heating at about 80160C is preferred.

Over the layer of the organopolysiloxane (A) thus obtained a solution ofthe organopolysiloxane is then applied (B) in an organic solvent in aproper manner to form an adhesive layer on the backing. For facilitatingthe formation of the adhesive layer, it is necessary that the samecuring catalyst, viz., benzoyl peroxide, dicumyl peroxide ordi-tert.-butyl peroxide is blended with the coating liquid and also thatafter the application, the adhesive layer is dried under heating at atemperature of about l00200"C.

The amount of the organopolysiloxane (A) to be applied to the backingaccording to the invention should be at the rate of at least 0.02 g/mpreferably at least 0.2 g/m while that of the adhesiveorganopolysiloxane (B) should be such that the organopolysiloxane (A)applied is within the range of from 0.0005 to 1, preferably from 0.005to 0.5, part by weight per part by weight of the organopolysiloxane (B).

DESCRIPTION OF THE DRAWINGS The adhesive tapes of the present inventionwill be illustrated with reference to the accompanying drawings. FIGS. 1and 2 show partial sections of the adhesive tape.

Adhesive tape shown in FIG. 1 comprises a backing 1, an under coat layer2 of organopolysiloxane (A) and an adhesive layer 3 oforganopolysiloxane (B). Adhesive tape shown in FIG. 2 comprises a glassfiber tape 1' coated with a surface coating agent such as polyimide,polyamideimide or organic fluorine-containing polymer, a layer 2 oforganopolysiloxane (A) and an adhesive layer 3 of organopolysiloxane(B).

The adhesive tapes obtained by the process of the present invention havea merit that, since organopolysiloxane (A) exhibits an excellent primingefiect on the adhesive layer of organopolysiloxane (B), the anchoringstrength of the adhesive layer to the backing is superior and,therefore, undesirable tear between the layers is not caused. Anothermerit of the adhesive tapes is that they have quite high strength ofadhesion to the surfaces of various materials and they can be peeledcompletely from the surfaces without transference of the adhesive layerto the surfaces.

DESCRIPTION OF SPECIFIC EMBODIMENTS The process of the present inventionwill be illustrated by way of the following Examples, in which parts areall by weight.

EXAMPLE 1 One side of a polytetrafluoroethylene tape of 0.05 mmthickness was treated with a solution of metallic sodium in liquidammonia. The surface was then coated with coating solution I of acomposition described below, air-dried and heat-treated at C for 10minutes to form 2.0 g/m of an under coat layer. The layer was coatedwith coating solution 11 of a composition also described below,air-dried and heat-treated at C for 15 minutes to form an adhesive layerof 0.03-0.04 mm thickness. Properties of the adhesive tape are as shownin Table 1.

In Comparative Example 1 in the Table, coating solution I was not used.In Comparative Example 2, coating solution 11 was not used but coatingsolution I- was applied to form a layer of about 0.04 mm thickness. Dataof Comparative Examples 1 and 2 are also shown in the Table. The data inTable 1 suggest that the adhesive tape prepared according to the processof the invention has excellent adhesive strength and that the adhesivelayer of the tape is not transferred to surfaces and, accordingly, highworkability of the tape is confirmed.

Coating solution I: Mixed solution comprising (1) 100 parts of 60percent solution in xylene of organopolysiloxane containing 5 molarpercent of phenyl group, 0.3 molar percent of vinyl group, based on thewhole organic groups and the remainder of methyl group, (2) 1.2 parts ofbenzoyl peroxide and (3) 200 parts of toluene, the organopolysiloxanebeing obtained by condensation reaction of 50 parts of a siloxanecopolymer composed of R SiO and SiO units (molar ratio 07:1) with 50parts of gum-like diorganopolysiloxane represented by the unit formula RSiO.

Coating solution 11: Mixed solution comprising (1) 100 parts of 60percent solution in xylene of an organopolysiloxane adhesive compositionobtained by condensation reaction of 55 parts of siloxane resin composedof (Cl-l SiO units and SiO units (molar ratio 0.75:1) with parts ofgum-like dimethylpolysiloxane, (2) 1.2 parts of benzoyl peroxide and (3)100 parts of toluene.

ane resin composed of R SiO and SiO unit (molar ratio 05:1) with partsof gum-like diorganopolysiloxane. 9942 559 23951!t sa lita a t appliedto Table 1 Present Comparative Comparative Invention Example 1 Example 2Quantity of coating solution l (g/m or film thickness) 2.0 g/m 0.04 mmQuantity of coating solution 11 (film thickness; mm) 0.04 0.03

Tensile strength (kg/25mm width) 12.9 12.9 12.8 Adhesive tape Elongation90 90 90 180 peel to stainless adhesion steel plate 720 660 450 strength(g/25mm width) to own backing 310 330 180 Unwind force (gl25mm width)470 430 510 Transference of adhesive layer to own backing o o 0 Transferof adhesive layer to the surface of subject Silicone rubber o x A note)Storage Neoprene rubber o x A at 50C Melamine o x x decorative Sheet for3 days Acrylic plate 0 x x after Glass plate 0 x x application 1Stainless steel 0 x x plate Storage at 200for 5 hours Stainless steel 0x x after plate application Note) Thermosetting silicone rubber oTransference was not recognized. A Partial transference was recognized.

it Transference was observed: inferior.

the same surface-treated polytetrafluoroethylene tape as in Example 1 invarious quantities as shown in Table 2. The surface was then coated withthe same coating solution 11 as in Example 1 to form adhesive layer.Properties of thus obtained adhesive tapes were as shown in Table 2.Data of Comparative Example 3 in the Table are those obtained by usingcoating solution 11 in place of coating solution 111 in the formation ofadhesive layer.

Table 2 Compara- Present Present Present tive inveninveninven- Example 3tion tion tion Quantity of coating solution 111 (glm) 0.02 0.2 2.0Quantity of coating solution 11 film thickness; mm) 0.04 0.04 0.04 0.04

Tensile strength Adhesive tape (kg/25 mm width) 12.8 12.9 12.9 12.9 s tqnfll 0, 29.

peel adhesion to stainless steel strength (gl25 mm plate 690 710 710 7201 width) m awn. a k n -..3e29-i 2.9 V 310 Table 2 Continued Compara-Present Present Present tive inveninveninven- Example 3 tion tion tionUnwind force (g/25 mm width) 460 460 450 470 Transference of adhesivelayer to own backing o o Transference of adhesive layer to the surfaceof subject Storage at 50C for Silicone rubber A x A A o 3 days afterapplication Silicone rubber B x A A o Neoprene rubber x A A 0 Storageunder 60g/cm Silicone rubber B x x A A at 50C for 3 days Neoprene rubberx x A 0 Pressure (g/cm Silicone rubber A x x x A Storage at 200C forSilicone rubber B x x x A one hour Pressure (40g/cm Silicon rubber A x xx A Silicone rubber B x x A o Silicone rubber A: Silicone rubber whichhardens at room temperature.

Silicon rubber B: Silicone rubber which hardens by heating.

EXAMPLE 3 Coating solution IV was preprared by mixing 100 parts of 60percent solution in xylene of organopolysiloxane containing 5 molarpercent, based on the whole organic group, of phenyl group, 0.3 molarpercent of vinyl group and the remainder of methyl group, and 200 partsof toluene, said organopolysiloxane being obtained by the condensationreactionof 50 parts of silox-i ane resin composed of R SiO units and SiOunits (molar ratio 07:1) with 60 parts of gum-like diorganopolysiloxane.

Coating solution IV thus obtained was then applied to a glass fiber tapecoated with polytetrafluoroethylene dispersion (the surface of which hadbeen treated previously with ammonium complex of sodium) in nearly thesame quantity as in Example I. The surparts of toluene.

face was further coated with coating solution 11' shown below to formadhesive layer of 0.03-0.04 mm thick. Properties of thus obtainedadhesive tape were as s o n n Iabl..3

Data of Comparative Example 4 in the Table are those obtained byapplying coating solution 11 in place of coating solution IV to theglass fiber tape in the format n,qfadhesiyslay ao ,7

Coating solution 11: Mixed solution comprising (1) 100 parts of 60percent solution in xylene of organopolysiloxane adhesive compositionobtained by the condensation reaction of parts of siloxane resincomposed of (CI-l SiO units and 810 units (molar ratio 0.65:1) withparts of gum-like dimethylpolysiloxane, (2) 1.2 parts of benzoylperoxide and (3) Table 3 Present Comparative Invention Example 4 Tapethickness (mm) 0.12 0.l2

Tensile strength (kg/25 mm width) 28.4 28.8 Adhesive tape Elongation 3 4peel adto stainless steel plate 600 580 hesion strength (g/25 mm width)to own backing 510 520 Unwind force (gl25 mm width) 550 530 Transferenceof adhesive layer to own backing o I o Transference of adhesive layer tothe surface of subiect Silicone rubber (Note*) 0 x Storage at Neoprenerubber o x 50C for Melamine plate 0 o 3 days after Glass plate 0 0application Acrylic plate 0 x Stainless steel plate 0 x Storage at 200Cfor 5 hours after Stainless steel plate 0 x application (Note f):Thermosetting silicone rubber EXAMPLE 4 Coating solution I used inExample 1 was applied to one side of a polyimide film (Kapton Film, aproduct of du Pont) of 0.025 mm thick and then dried to form 10therefore, its workability is excellent.

7 EXAMPLE Coating solution I used in Example 1 was applied to one sideof a polyamideimide film (TH-1000 50 film,

Adhesive tape an under coat layer of 4 g/m Thereafter, the coating 5 aproduct of Toray Co.) of 0.05 mm thick and then solution II was appliedonto the layer to form an adhedried to form an under coat layer of 2 g/mThereafter, sive layer of 0.03-0.04 mm thick. The properties of thecoating solution I1 used in Example 3 was applied onto adhesive tapethus obtained are as shown in Table 4. the layer to form an adhesivelayer of 0.03-0.04 mm Data of Comparative Example 4 in the Table werethick. Properties of the adhesive tape are as shown in obtained in theabsence of coating solution I. From the Table 5. data, it is confirmedthat the adhesive tape obtained ac- Data of Comparative Example 5 in theTable were cording to the process of the invention has high adheobtainedby applying coating solution 11 in place of sive strength and that it isfree from transference of the coating solution I in the formation of theadhesive .?Q l Y l3XF ptlts ztass aw qh it i appliedandi e T able 4Present Comparative invention Example 4 Quantity of coating solution I(g/m 4.0

Quantity of coating solution ll (film thickness; mm) 0.03 0.03

Tensile strength (kg/ mm width) 5.6 5.8

Adhesive tape Elongation 70 70 180 peel adto stainless steel plate 650630 hesion strength (g/25 mm width) to own backing 620 610 Transferenceof adhesive layer to own backing o o Transference of adhesive layermeiufamtgbjec W Silicon rubber plate 0 x (Note Storage at Neoprenerubber plate 0 x 50C for Melamine decorative o A sheet 3 days afterCopper plate 0 A application Stainless steel plate 0 Storage at V 200Cfor Stainless steel plate 0 x 8 hours after application Copper plate 0 A(Note Thermosetting silicone rubber.

o I Transference was not observed. A Partial transference was observed..I193???i !.9l$ ll flflm Table 5 Present Comparative Invention Example 5Quantity of coating solution 1 (g/m 2.0

Quantity of coating solution 11" (film thickness; mm) 0.03 0.03

Tensile strength (kg/25 mm width) 10.9 10.8

Elongation 38 180 peel adto stainless steel plate 680 660 hesionstrength (g/ZS mm width) to own backing 730 700 Transference of adhesivelayer to own backing o 0 Transfer of the adhesive layer to the surfaceof subject Storage at Silicone rubber plate A x C for Stainless steelplate 0 o 3 days after Neoprene plate 0 x application Copper plate 0 AStorage at Stainless steel plate 0 A 200C for 8 hours after Copper plate0 A application 11 EXAMPLE 6 Coating solution V of a composition shownbelow was applied to one side of a soft aluminum foil of 0.08 mm thickwhich had been polished by sand blast treatment. Thus obtained layer wasthen dried to form an under coat layer of 4 g/m Thereafter, coatingsolution 11 used in Example 1 was applied onto the layer to'form anadhesive layer of 0.04 mm thick. Properties of the adhesive tape thusobtained are as shown in Table 6.

Data of Comparative Example 6 in the Table were obtained by applyingcoating solution 11 in place of coating solution V in the formation ofthe adhesive layer.

Coating solution V: Mixed solution.comprising (l) 100 parts of 60percent solution in xylene of organopolysiloxane containing 3 molarpercent, based on the 'wh ol o rganic groups, of phenyl group, 1.2 molarpercent of vinyl group and the remainder of methyl group, (2) 1.2 partsof benzoyl peroxide and (3) 200 parts of polysiloxane (A) being obtainedby partial condensation of 30-70 parts by weight of a copolymer- (a)composed of SiO and R SiO units, wherein R is selected from substitutedand unsubstituted monovalent hydrocarbon groups, in a molar ratio offrom 110.4 to 1:1 with 70-30 parts by weight of a diorganopolysiloxane(b) composed of R SiO units, wherein R is selected from substituted andunsubstituted monovalent hydrocarbon groups, said units containing amember selected from the group consisting of hydroxyl and vinyl at theend of the units molecular chain, and having a viscosity of more than100,000 centistokes at C.

2. The adhesive tape according to claim 1, in which saidorganopolysiloxane (B) comprises the partial condensation product of -70parts by weight of a copolymer (0) composed of SiO and (CH SiO units ina molar ratio of from 110.4 to 1:1 with 70-30 parts by weight ofdimethylpolysiloxane gum (d).

3. The adhesive tape according to claim 1, in which said copolymer (a)is composed of SiO and R SiO toluene, the organopolysiloxane beingobtained by con- 20 densation reaction of parts of siloxane resincomumts m amok-r twp-Of from posed of R SiO units and SiO; units (molarratio 4. The adhesive tape according to claim 1, in which 0.621) withparts of gum-like diorganopolysiloxane said organopolysiloxane (A)contains l-7 molar perrepresented by the unitformula cent of phenylgroups and 0.1-2 molar of vinyl Table 6 Present Comparative InventionExample 6 Quantity of coating solution V (g/m) 4.0

Quantity of coating solution 11 (film thickness; mm) 0.04 0.04

Tensile strength (kg/25 mm width) 10.4 10.6 Adhesive tape Elongation 7 9Transference of adhesive layer to own backing o x Transference ofadhesive layer to the surface of substrate Storage at Silicone rubberplate A x 50C for Neoprene rubber plate A x 3 days after Stainless steelplate 0 x application Copper plate 0 x Storage at Stainless steel platex 200C for 8 hours after Copper plate A x application What is claimedis: 1. Adhesive tape which comprises (1) an undercoat layer oforganopolysiloxane (A) containing 0.2-10

molar percent of the phenyl group, 0.005-5 molar per- 50 groups, basedon the whole of said organic groups.

5. The adhesive tape according to claim 1, in which said backing iscomposed of glass fiber tape the surface of which is coated with amember selected from the group consisting of polyamide, polyamideimide,and organic fluorinecontaining polymer.

6. The adhesive tape according to claim 1, in which said organicfluorine-containing polymer is selected from the group consisting ofpoly-tetrafluoroethylene, polytetrafluoromonochloroethylene andcopolymer of tetrafluoroethylene and hexafluoropropylene.

1. ADHESIVE TAPE WHICH COMPRISES (1) AN UNDERCOAT LAYER OFORGAOPOLYSILOXANE (A) CONTAINING 0.2-10 MOLAR PERCENT OF THE PHENYLGROUP 0.005-5 MOLAR PERCENT OF THE VINYL GROUP, THE MOLAR PERCENTAGESBEING BASED ON THE WHOLE OF THE ORGANIC GROUPS, AND THE REMAINDER OFSAID GROUPS BEING SUBSTANTIALLY THE METHYL GROUP, SAID UNDERCOAT LAYERBEING COATED ON A BACKING WHICH COMPRISES A MEMBER SELECTED FROMPOLYAMIDE, POLYAMIDE-IMIDE, AND ORGANIC FLUORINE-CONTAINING POLYMER, ANDMETAL FOIL AT LEAST AT THE SURFACE OF SAID BACKING, AND (29 AN ADHESIVELAYER PLACED ON SAID UNDERCOAT LAYER COMPRISING ORGANOPOLYSILOXANE (B),SAID ORGANOPOLYSILOXANE (A) BEING OBTAINED BY PARTIAL CONDENSATION OF30-70 PARTS BY WEIGHT OF A COPOLYMER (A) COMPOSED OF SIO2 AND R3SIO0.5UNITS, WHEREIN R IS SELECTED FROM SUBSTITUTED AND UNSUBSTITUTEDMONOVALENT HYDROCARBON GROUPS, IN A MOLAR RATIO OF FROM 1:04 TO 1:1 WITH70-30 PARTS BY WEIGHT OF A DIORGANOPOLYSILIXANE (B) COMPOSED OF R''2SIOUNITS, WHEREIN R'' IS SELECTED FROM SUBSTITUTED AND UNSUBSTITUTEDMONOVALENT HYDROCARBON GROUPS, SAID UNITS CONTAINING A MEMBER SELECTEDFROM THE GROUP CONSISTING OF HYDROXYL AND VINYL AT THE END OF THEUNIT''S MOLECULAR CHAIN, AND HAVING A VISCOSITY OF MORE THAN 100,000CENTISTOKES AT 25*C.
 2. The adhesive tape according to claim 1, in whichsaid organopolysiloxane (B) comprises the partial condensation productof 30-70 parts by weight of a copolymer (c) composed of SiO2 and (CH3)SiO0.5 units in a molar ratio of from 1:0.4 to 1:1 with 70-30 parts byweight of dimethylpolysiloxane gum (d).
 3. The adhesive tape accordingto claim 1, in which said copolymer (a) is composed of SiO2 and R3SiO0.5units in a molar ratio of from 1:0.5 to 1:0.8.
 4. The adhesive tapeaccording to claim 1, in which said organopolysiloxane (A) contains 1-7molar percent of phenyl groups and 0.1-2 molar % of vinyl groups, basedon the whole of said organic groups.
 5. The adhesive tape according toclaim 1, in which said backing is composed of glass fiber tape thesurface of which is coated with a member selected from the groupconsisting of polyamide, polyamideimide, and organic fluorinecontainingpolymer.
 6. The adhesive tape according to claim 1, in which saidorganic fluorine-containing polymer is selected from the groupconsisting of poly-tetrafluoroethylene,polytetrafluoromoNochloroethylene and copolymer of tetrafluoroethyleneand hexafluoropropylene.